Electrostatic Spraying Method Research Articles

Hydrate Decomposition Inhibitors by Phase Change Cooling Storage Based on an Electrostatic Spraying Method

Hydrate Decomposition Inhibitors by Phase Change Cooling Storage Based on an Electrostatic Spraying Method

Electrostatic Spraying Microspheres of Nano Boron and Its Constant-Volume Combustion with Potassium Nitrate

ABSTRACT The nanometer boron (nB) powders have become the most promising high-energy additive in the field of fuel-rich solid propellants due to their extremely high gravimetric and volumetric calorific value. However, further applications are limited by its disadvantages such as easy agglomeration, easy oxidation, high ignition temperature, and incomplete energy release. Herein, nB powders were pre-agglomerated into microspheres by electrostatic spray method using fluoropolymer (F2602) as binders. The morphology and structure of the samples were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray energy spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), and Brunauer-Emmett-Teller (BET). Results showed that the pre-agglomerated nB microspheres had good dispersion, high sphericity, and no surface oxide. The thermal performance and combustion performance of the samples were characterized by a synchronous thermal analyzer and combustion pressure test device. Results showed that the nB microspheres had the highest oxidation weight gain within 1000°C and lowest activation energy compared to the same scale micron boron. In addition, the microspheres significantly shorten the combustion time and improve the combustion efficiency.The pressurization rate of nB microspheres is 4.12 times that of micron boron powders and 2.85 times that of nB powders. These excellent properties may be related to its unique spherical porous structure. Therefore, the preparation of nB microspheres with controllable structure by electrostatic spraying has a good application prospect.

Drug Release and Biocompatibility of a Paclitaxel-Coated Balloon Prepared Using the Electrostatic Spray Method

Paclitaxel-coated balloons (PCBs) have become effective treatment options for vascular disease, but long-term drug release and biocompatibility are influenced by the drug patterns. In this work, paclitaxel coatings were prepared via electrostatic spraying, and the effect of D-tartaric acid additives was investigated. Microstructures and surface morphology were studied using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), respectively. Drug release was measured in vitro, and biocompatibility was evaluated using the haemolysis rate, platelet adhesion and activation, protein adsorption, cell adhesion, and cell proliferation. Our results showed that a uniform crystalline paclitaxel drug coating was obtained, and that the pattern and release of paclitaxel was influenced by the content of D-tartrate. The contact angle of all coatings was less than that of nylon 12. The drug coatings prepared at a mass ratio of paclitaxel to D-tartaric acid of 2:1 had the highest drug release in a brief period of time. The haemolysis rate of the drug coating was less than 5%. Compared with the control samples, platelet adhesion and activation were significantly reduced, albumin adsorption was increased, and the adsorption of fibrinogen was reduced on the surface of the drug coating. Endothelial cells demonstrated good proliferation after three days of cell culture. Therefore, PCBs with specific patterns have good biocompatibility and drug release, with potential clinical applications in vascular disease.

Construction of hollow heterogeneous microspheres containing energy storage fibers by electric spray to promote combustion of nano aluminum

To solve the problem of nano-aluminum (nAl) powder easy agglomeration and improve its thermal reaction, nAl was combined with adhesive (Viton A, F2602) and oxidizer (Ammonium perchlorate, AP) forming microspheres by electrostatic spray method. The morphology and structure were analyzed by SEM, EDS and XPS. The results showed that the microspheres (diameter≈Φ10–15 μm) were hollow structures formed by winding of fluoropolymer fibers, while AP and nano aluminum particles were embedded on the fibers. By controlling the electric spray process, the well-dispersed AP and nAl nanocrystals were assembled on the fiber. Thermal analysis indicated that the gas phase products decomposed by AP were absorbed by porous microspheres, and part of the heat was stored in polymer fibers, thus promoting the breakdown of the alumina shell and accelerating the pre-ignition reaction. The combustion and laser ignition experiments proved hollow heterogeneous microspheres have excellent thermodynamic properties. The assembled microspheres not only solved the problem of poor rheology caused by the agglomeration of nAl, but also improved the insufficient combustion of nAl and the condensation of products.

Coaxial electrostatic spray-based preparation of localization missile liposomes on a microfluidic chip for targeted treatment of triple-negative breast cancer

Due to triple-negative breast cancer (TNBC) lacking specific targets for efficient therapies, nanoparticles have been widely developed to enhance efficacy and reduce the toxicity of chemotherapeutics. We prepared unique liposomes containing PTX and DOX by microfluidics-based coaxial electrostatic spray method, which have a uniform particle size, high drug loading capacity, and good stability. Meanwhile, the cRGD peptide was fused with the lipid membrane to form PTX/DOX@cRGD-Lipo, which played a GPS role in locating tumor neovascularization and further targeting TNBC cells where both overexpress αvβ3. The PTX/DOX@cRGD-Lipo showed synergistic anti-tumor activity of double drugs and enhanced tumor cell apoptosis. Fluorescence microscopy and flow cytometry showed that the co-loaded targeted liposomes could be effectively absorbed by MDA-MB-231 and 4T1 cells and then released the content. In addition, the PTX/DOX@cRGD-Lipo presented excellent targeting biodistribution in vivo and a higher tumor growth inhibition rate in the orthotopic tumor mouse model. All results suggested that the double drug-loaded targeted liposome could be a promising treatment modality for TNBC.

Electrostatic spraying preparation of Si/NiF2/PVDF energetic composites and their reaction characteristics

Metastable intermolecular composites are widely used in energy-demanding fields, where metal fluorides/fluoropolymers as oxidants have been a hot research topic in recent years. In this study, Si/NiF2/PVDF ternary energetic composites were prepared by the electrostatic spraying method for the first time, where NiF2 functions as the oxidant. At the same time, PVDF serves as both the oxidant and the binder. The energetic characteristics of the samples were studied through thermal analysis and preliminary ignition and combustion tests. It is found that the prepared samples are generally in the form of microspheres, in which PVDF binds Si and NiF2 particles together. The addition of Si nanopowder can promote the early decomposition of NiF2, which can improve reactivity. Compared with a physically mixed counterpart, the exothermic reaction between Si and PVDF in microspheres starts at lower temperatures and proceeds to more completion. The electrostatically sprayed sample also shows a shorter combustion time and a more intense luminescence phenomenon.

Preparation of diatomite-based SA@ZIF-8 composite microspheres by electrostatic spray method and its adsorption performance for Cu(II)

Diatomite (DE)-based sodium alginate (SA) loaded ZIF-8 composite microspheres were prepared by high-voltage electrostatic spray technology. SA/DE microspheres were prepared by SA and acid-base-regulated silica sol solution. Ultra-small ZIF-8 was grown on SA/DE microspheres by in-situ synthesis method to obtain ultra-high specific surface area composite microspheres. The morphology and particle size of the composite microspheres were analyzed by SEM, and characterized by FT-IR, XRD and TGA. The optimum adsorption efficiency were achieved by a series of conditions optimization. The adsorption of Cu(II) by SA/DE@ZIF-8 conforms to the Langmuir adsorption model, and the theoretical maximum adsorption capacity is 599.07 mg/g. In summary, this study opens up a new strategy for the design of efficient and easily recycled ZIF-8 composite microspheres for water treatment.

Preparation and characterization of Al@TKX-50@NC composite microspheres by electrospray

Micro-nano composite energetic materials have attracted extensive attention from researchers due to their excellent properties. Electrostatic spray drying, as an emerging composite material preparation technology, has an important impact on the assembly and energy release regulation of energetic materials. In this paper, NC with excellent mechanical properties was selected as the energetic binder. The uniform assembly of TKX-50 and Al was achieved by electrostatic spraying technology, and Al@TKX-50@NC micro-nano composite energetic material microspheres were prepared. The structure and composition of the composite were characterized, and its thermal decomposition kinetics and thermodynamics were calculated and analyzed. At the same time, its ignition and combustion performance were tested. It is found that the samples prepared by electrostatic spray are regular spherical, and the particle size is about 1–6 μm. Compared with the physical mixture samples, the Al@TKX-50@NC composite microspheres not only have a more complete oxidation reaction but also have better ignition and combustion performance. The results show that the electrostatic spray method is very effective in improving the energy release of composite energetic materials.

Preparation of Si@PVDF composite microspheres by electrostatic spraying for enhanced energetic characteristics

In this study, Si@PVDF composite microspheres are prepared by the electrostatic spraying method. The spheres are with average diameter of around 2 μm (when at ideal stoichiometry), within which Si nanopowder is uniformly distributed. The exothermic properties of samples are studied through simultaneous thermogravimetry and differential scanning calorimetry. Benefiting from the improved interfacial contact quality, Si@PVDF shows increased chemical reactivity in terms of reduced reaction onset temperature, peak temperature and apparent activation energy than those of physically mixed Si/PVDF counterpart. Si/PVDF cannot be ignited through Joule heating, either in the powder of pellet form, while self-sustained combustion propagation is observed for Si@PVDF pellets. The combustion behaviors of Si@PVDF pellets are systematically studied in open-air (where light signal is analyzed) and constant-volume (where pressure signal is analyzed) conditions. The results show that the combustion process is influenced by the equivalence ratio, porosity of the pellet and the accessibility of O2 gas in the environment. Overall, the encapsulation of Si nanopowder into PVDF microspheres using electrostatic spraying shortens the mass and heat transfer distance and thus realizes enhanced energetic characteristics.

Hydroxyapatite microbeads containing BMP-2 and quercetin fabricated via electrostatic spraying to encourage bone regeneration

BackgroundHydroxyapatite (HAp) possesses osteoconductive properties, and its granular form can serve as an effective drug delivery vehicle for bone regeneration. Quercetin (Qct), a plant-derived bioflavonoid, is known to promote bone regeneration; however, its comparative and synergistic effects with the commonly used bone morphogenetic protein-2 (BMP-2) have not been investigated.MethodsWe examined the characteristics of newly formed HAp microbeads using an electrostatic spraying method and analyzed the in vitro release pattern and osteogenic potential of ceramic granules containing Qct, BMP-2, and both. In addition, HAp microbeads were transplanted into a rat critical-sized calvarial defect and the osteogenic capacity was assessed in vivo.ResultsThe manufactured beads had a microscale size of less than 200 μm, a narrow size distribution, and a rough surface. The alkaline phosphatase (ALP) activity of osteoblast-like cells cultured with the BMP-2-and-Qct-loaded HAp was significantly higher than that of either Qct- or BMP-2-loaded HAp groups. The mRNA levels of osteogenic marker genes such as ALP and runt-related transcription factor 2 were found to be upregulated in the HAp/BMP-2/Qct group compared to the other groups. In micro-computed tomographic analysis, the amount of newly formed bone and bone surface area within the defect was significantly higher in the HAp/BMP-2/Qct group, followed by the HAp/BMP-2 and HAp/Qct groups, which is consistent with the histomorphometrical results.ConclusionsThese results imply that electrostatic spraying can be an efficient strategy to produce homogenous ceramic granules and that the BMP-2-and-Qct-loaded HAp microbeads can serve as effective implants for bone defect healing.

Electrostatic spray catalytic particle coating on carbon electrode for enhancing electrochemical reaction

The uniform coating of catalytic materials on the electrode surface is essential for improving the performance of electrochemical reactions. In this study, the electrostatic spray coating technique is used to deposit Molybdenum disulfide (MoS2) particles on carbon electrodes and examine the electrochemical hydrogen evolution reaction (HER) performance in a 0.1 M H2SO4 electrolyte. The experimental results reveal that the electrostatic spray coating method achieves a more uniform coating MoS2 catalyst particles on the carbon fiber substrate. It provides good adhesion for electrocatalyst binding on the carbon paper electrodes. During HER analysis, a 25% higher current density is obtained from the electrostatic spray-coated electrodes compared to the manual spray-coated electrode at a potential of 0.95 V. Electrochemical impedance spectroscopy, and electrochemical surface area measurements indicate the superior electrochemical characteristics of the electrostatic spray-coated electrode. The faradaic efficiency of the electrostatic spray-coated electrode is close to 100% at a high applied potential of −1.6 V with a 0.0059 L volume of hydrogen generation. Moreover, chronoamperometric measurements demonstrate the excellent durability of the electrostatic spray-coated carbon electrodes. This study suggests that the facile electrostatic spray method is efficient for coating electrodes with high uniformity and good adhesion for various electrochemical applications.

A one step self-cleaning surface with robust superhydrophobic and photocatalytic properties: Electrostatic sprayed fluorinated ethylene propylene mixed with nano TiO2–SiO2 particles

In this research, a one-step and environmentally friendly method, free from the complexity of chemical techniques, was utilized to prepare a superhydrophobic surface that can be implemented on large scale. To this end, at first, silica nanoparticles were made hydrophobic through the silanization method, then got mixed with titanium dioxide nanoparticles and fluorinated ethylene propylene (FEP). Afterward, the combined materials were deposited on aluminum substrate using an electrostatic spraying method. In order to assess the fabricated surface, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and contact angle measurement are accomplished. In addition, the photocatalytic activity by the degradation of oleic acid and methylene blue (MB) upon UV exposure was studied. Results indicated formation of a superhydrophobic photocatalyst with contact angle over 150 ° . This superhydrophobic surface containing nano silica content 12 wt.% and TiO 2 20 wt.% exhibited excellent photocatalytic activities in the organic materials degradation. The obtained photocatalyst surfaces also revealed proper stability in acidic (pH = 5) and alkaline (pH = 11) media. Moreover, a suitable stability was observed in the fouling medium with duration 10 h while no change in the static contact angle occurred.

Biology and nature: Bionic superhydrophobic surface and principle.

Nature is the source of human design inspiration. In order to adapt to the environment better, creatures in nature have formed various morphological structures during billions of years of evolution, among which the superhydrophobic characteristics of some animal and plant surface structures have attracted wide attention. At present, the preparation methods of bionic superhydrophobic surface based on the microstructure of animal and plant body surface include vapor deposition, etching modification, sol-gel method, template method, electrostatic spinning method and electrostatic spraying method, etc., which have been used in medical care, military industry, shipping, textile and other fields. Based on nature, this paper expounds the development history of superhydrophobic principle, summarizes the structure and wettability of superhydrophobic surfaces in nature, and introduces the characteristics differences and applications of different superhydrophobic surfaces in detail. Finally, the challenge of bionic superhydrophobic surface is discussed, and the future development direction of this field is prospected.

Engineering of macroscale graphene oxide quantum dots skeleton membrane via electrostatic spraying method

In order to construct an efficient separation channel of graphene oxide quantum dots (GOQDs) membrane, a novel macroscale GOQDs skeleton membrane with the ethylenediamine (EDA) as the bridging agent was prepared for the first time by uniformly covering GOQDs nanosheets (∼2.78 nm) and EDA on the surface of the substrate membrane via electrostatic spraying method. The structure of the membrane was further optimized by post-crosslinking with trimesoyl chloride (TMC), and obtained the c-GOQDs skeleton membrane. The effects of spraying time and post-crosslinking on the structure and properties of as-prepared membranes were studied. The results showed that the obtained macroscale GOQDs skeleton membrane exhibited excellent separation effect for salt and dye. The introduction of EDA reconstructed the structure of the GOQDs skeleton separation layer, which made the separation layer structure loose and contributed to accelerating the water transmission speed. Thus, the permeation flux of GOQDs skeleton membrane (M-2, 155.6 L m−2 h−1, 3 bar) with similar dye rejection and lower bivalent salt rejection, was near 5 times than that of pure GOQDs membrane. Moreover, post-crosslinking could further improve the Congo Red rejection of c-GOQDs skeleton membrane (99.5%) with the higher salt/dye selectivity, which also showed high long-term operation stability and presented a potential application in dye desalination field.

Preparation of corn starch/rock bean protein edible film loaded with d-limonene particles and their application in glutinous rice cake preservation

Glycerol hydrogenated rosin (GEHR) and d-limonene were prepared for micro-particles by electrostatic spray method. When the GEHR/d-limonene ratio is 5.5:4.5 and the electrostatic spray extrusion speed is 1 mL/h, the best particle size (177.24 ± 17.09 μm) and embedding rate of d-limonene (41.74 ± 9.88%) are achieved. Then, rock bean protein (RP) was extracted from wild rock beans and combined with GEHR/d-limonene particles and corn starch (CS) to prepare a new type of edible film. The prepared film was characterized using Fourier transform infrared spectroscopy in terms of structural changes and physical, optical, mechanical, and thermal properties. The results show that the edible film with a ratio of 1:1 exhibited more optimized thermal (179.2 °C) and mechanical properties (TS 0.88 MPa, EAB 54.36%). Studies on freshly prepared glutinous rice cake as an object for preservation using edible film show that the films can prolong shelf life by ~2–4 d. Through this experiment, it can serve as a reference for the development of a new type of edible film.

Electrostatic Deposition of Bio-Composite Polymer/Hydroxyapatite Coatings on 316L Stainless Steel

The present work aims to prepare polymer-based biocomposite coated layers by electrostatic spray method onto a 316L stainless steel substrate. Different percentages of ( 2,4, and 8) wt.% of Hydroxyapatite (HA) with (98,96, and92) wt.% of PMMA were used to prepare the composite coating. Wettability, phase composition, and surface morphology were studied using contact angle measurement, X-ray diffraction, and scanning electron microscopy techniques respectively. The results revealed that a homogenous, uniform, and crack-free coating layers were obtained. The wettability testing indicated increased hydrophobicity of the coatings with the addition of hydroxyapatite particles where the 8wt.%HA applied the highest contact angle of (104.08o).The average thickness was about (400µm) for the coating layer deposited on the substrates using the electrostatic technique, whereas the average diameter coating was about (33.95µm).

Preparation and Characterization of Self-Healing Polyurethane Powder Coating Using Diels-Alder Reaction.

Although powder coating systems offer many environmental, ecological and energy related benefits over liquid based coatings, in the case of uretdione based polyurethane systems, high curing temperature is still an issue. On the other hand, powder coating systems make it possible to reduce the costs and enhance the process of forming complex 3D structures using the deep drawing method by pre-coated metal substrates. During this processing method, there is a probability of micro crack formation in the coated film due to strain impact on the coating layer. A powder coating with self-healing ability is an ultimate solution to face not only this kind of fraction but also any other possible ones (such as defects caused by any impact on film surface during processing, transporting or even service). Here, a single molecule that is prepared via Diels–Alder cycloaddition reaction and retro Diels–Alder cleavage reaction was utilized as a self-healing additive to achieve self-healing ability in the powder coating system that is based on a commercially available uretdione cross-linker and OH-polyester resin. Coatings were prepared through melt mixing of components in a lab mixer, milling, sieving, and then application on the metal substrate through the electrostatic spraying method. To illustrate the role of self-healing additive, various concentrations (4 and 9% wt.) in combination with different curing temperatures (80 °C to 200 °C) were investigated. Both samples containing HA showed self-healing ability at elevated temperature around 120 °C for about 30 min with acceptable roughness and surface properties. Hardness measurement of cured film as well as thermal investigation indicate the chemical reaction of HA in a cross-linked network of cross-linker and resin. In addition, using HA leads to a 40 K drop in curing temperature of the system without using any catalyst. A 2.58% improvement in hardness values at a lower curing temperature and healing time of around 12.5 min at 120 °C to recover 100% of initial scratch (more than 10 cycles) in the sample containing 9% wt. HA was observed.

Development of CaO-rich blast furnace slag containing fluorine mica-based glass ceramic coatings

In the present study, Blast Furnace Slag (BFS) waste was evaluated as a sustainable, cost-effective CaO, SiO2, Al2O3 and MgO substitute for inorganic oxides for the production of frit, a raw material for glass ceramic production. Two different frits were prepared to compare a commercially available frit (F-STD) with frit produced using BFS waste (F-BFS). The samples were characterized by XRF, XRD, heating microscopy, dilatometry and TG-DTA to determine the chemical composition, phase formation and thermal properties. The frits were applied on steel using the electrostatic spray method and subsequently thermally treated at 830 °C for 4.5 min. The reference (GC-STD) and partially BFS-substituted glass ceramic (GC-BFS) coatings were examined by XRD, SEM-EDS and ICP-MS experiments. The main crystal phase for both samples was Ni-substituted fluorine mica (KLiNi2Si4O10F2). GC-BFS was slightly more amorphous (70%) than GC-STD (69.1%), which was correlated with the thermal properties of the BFS waste. Likewise, ICP-MS analysis after a boiling citric acid test (ISO 28706-1: 2008) revealed that the GC-BFS had relatively higher chemical resistance. The total release from the reference sample (GC-STD) was 23.556 mg/L, whereas the total release from the sustainably produced sample (GC-BFS) was 21.451 mg/L, which was consistent with the XRD results.

Morphology and Mechanical Properties of a Composite Coating by Electrostatic Dry Spray Method

Powder spray coating was used for many applications such as paint decoration and protection against corrosive environments. The electrostatic spray method is used to lower the manufacturing cost and the environmental effect during the production process. It is done by electrostatic device and spray gun to create a layer on the substrate to play a protective role. Different dry powders were mixed to form a composite mixture consisted of Al2O3 and SiC or ZrSiO4 with Al powder as a binder. The powders mixture was deposited by electrostatic spray technique with a high voltage of 15 kV on a low carbon steel substrate of (40 x 10 x 4) mm in dimensions. Two groups of mixtures were used to form the coating layers. Powders of Al2O3 with (20 and 40) weight percent (wt%) of SiC as the first group and (20 and 40) wt% of ZrSiO4 as the second group were used. 5 wt% of Al powder was added as a binder, and the samples were heat treated at 900 C° for 2 hours. A detailed characterization of the composite coating layers was performed using XRD, SEM, and EDX, as well as, micro-hardness measurements. The obtained surface composite layers were smooth and having good particle distribution which leads to enhance roughness values (Ra). Furthermore, the hardness increased with increasing the amount of carbide and zirconia, and the obtained layers show no presence of defects or cracks.

Al2O3-TiO2-PMMA Bio-Composite Coating Via Electrostatic Spray Technique

This work aims preparation of polymer-based biocomposite coating by electrostatic spray method onto 316L stainless steel substrate, the present work will compare the effects of incorporation of Al2O3 and TiO2 particles at a different percentage of (10,15 and 20 % wt. from Al2O3 and TiO2 with (90,85 and 80% wt. PMMA - based electrostatic deposition coating is studied. The structure and chemical composition of composite coatings were studied by using (SEM) & (EDS) and mechanical properties (Microhardness and adhesion strength) of Al2O3-TiO2-PMMA composite coating. The SEM&EDX result showed that the composite coating to be dense with uniform dispersants and continuous with a well homogenous mixture within coating exhibits a much-increased Microhardness and remarkably improved adhesion strength.